Columbium-base alloy



United States Patent 3,379,519 COLUMBIUM-BASE ALLOY Gordon D. Gemmell,Wilmington, Del., assignor, by mesne assignments, to Union CarbideCorporation, a corporation of New York No Drawing. Continuation-impartof application Ser. No. 72,846, Dec. 1, 1960. This application Dec. 11,1961, Ser. No. 158,566

1 Claim. (Cl. 75--174) Patented Apr. 23, 1968 atmosphere in the furnace.The alloy thus prepared was cast into a tapered ingot three inches inlength, and this ingot was machined to form a cylinder /2 inch indiameter. This cylinder was heated in argon to 800 C. and was swaged toa reduction in cross-sectional area, cooled in air, and descaled andmachined to prepare it for testing for high-temperature strengthproperties.

The test specimen was heattreated in an electric furnace for nine hoursat 2000 C. in vacuum, cooled to room temperature, and was then testedfor tensile strength in vacuum at a temperature of 1100 C. Results ofthis testing are given in Table I below.

EXAMPLE 2 Following the same procedure as given in Example 1, an alloyof 10% zirconium, 10% tungsten, balance columbium, was prepared byblending and melting 45.4 parts of zirconium, 45.4 parts of tungsten,and 363.2 parts of columbium. An ingot was prepared and the alloy testedin the same manner as described in the preceding example. Results aregiven in Table I below.

TAB LE I [Tensile strength testing of N b-ZrW AlloysHeat treatment: 9hrs. at 2,000" C.Tested in vacuum at l,100 C. at a strain rate or 0.067per minute] Percent Strength Ductility Composition Percent Percent 0.2%Ultimate Reduction Elongation Zr W Nb Yield Tensile in Cross in Gauge(p.s.i.) (p.s.i.) Sectional Length;

Area 0.125 Diam.

Alloy of Example:

1 5 1O Bal. 58,400 59,900 14 3 2 10 10 Bal. 54,900 56,000 5 3 [Theseresults may be compared with the following control tests under the sameconditions] Control Sample:

7, 740 8, 91 32 None Bal. *33, 800 0 0 None Bal. 37, 600 38, 900 8 2None Bal. 36, 900 38, 900 2 2 None Bal. 48, 600 48, 600 3 1 None Bal.50, 900 51, 200 0 0 *Fracture strength: Brittle fracture.

ments may be made to this alloy in order to impart to it certain otherdesirable characteristics, for example, increased workability of thealloys. More specifically, the alloys of this invention may contain upto 2.0% in total of one or more of the following elements: hafnium,thorium, yttrium, and the rare earth elements of atomic numbers 58 to71, inclusive, and up to 0.2% in total of one or more of the elementsboron and carbon. The rare earth elements of atomic numbers 58 to 71 arecerium, praseodymium, neodymium, promethium, Samarium, europium,gadolinium, terbiurn, dysprosium, holmium, erbium, thulium, ytterbium,and lutetium.

For a clearer understanding of the invention, the following specificexamples are given. These examples are intended to be merelyillustrative of the invention 'and not in limitation thereof. Thecompositions are expressed in terms of weight percent as determined bythe weight of the starting materials used. All tensile tests areaccording to the recommendations of the A.S.T.M. Designation E21-58T,and stress rupture testing is carried out according to practicesrecommended by the A.S.T.M. Standards Committee and given in DesignationEl39-58T.

EXAMPLE 1 An alloy comprising 5% zirconium, 10% tungsten, balancecolumbium, was prepared and tested for strength at high temperature asfollows:

45.4 parts of powdered tungsten, 22.7 parts of zirconium sponge, and385.9 parts of powdered columbium were blended and melted in a tungstenarc furnace using a water-cooled copper crucible, and maintaining aninert EXAMPLES 3 TO 7, INCLUSIVE Other alloys of this invention wereprepared .in the same manner as given in Examples 1 and 2. These were 0heat treated in the same way and were subjected to stress-rupturetesting at elevated temperatures. Results of these tests are given inTable II below.

TABLE II [Stress-rupture testing of Nb-Zr-W alloys-Heat treatment: 9hrs. at,

[These results may be compared with the following tests made under thesame conditions] Nb Metal 7, 750 0. 15 27 Control Alloy:

#1 1 None Bal. 17,500 0.5 3 #2 5 None Bal. 17,500 3. 8 5 #3 10 None Bal.22,500 0, 3 4 #4 10 None Bal. 22, 000 0. 4 3 #5 20 None Bal. 22, 500 0.23

An alloy of the composition of Example 5 (5 Zr, 15 W, bal. Nb) wasfabricated into grips which were used for tensile testing andstress-rupture testing of refractory alloy specimens at high temperaturein vacuum.

EXAMPLE 8 carbon, etc., which are initially present in the constituentelements. Certain of these impurities will to some extent affect theproperties of the alloys, and in adding the optional elements which havebeen heretofore specified, the quantity of these elements present asimpurities should be taken into consideration in determining the totalamount of such elements present in the alloy.

The alloys of this invention will be found useful as materials ofconstruction where a high-temperature refractory alloy is required forlong service at temperatures of 1000 C. and above. For example, they areparticularly suitable as supports and linings in furnaces used for thehigh-temperature treatment of metals in vacuum or in inert gases. It isalso contemplated to coat or clad the An alloy was prepared as given inExample 1, except that the composition of the alloy was 5% zirconium,10% tungsten, 0.05% boron, and the balance columbium. This alloy wasprepared by melting together 45.5 parts tungsten powder, 22.7 partsZirconium sponge, 11.4 parts of a master alloy comprising 2% boron byweight, balance columbium, and 374.6 parts of columbium powder. Theingot was prepared for testing in the manner described in Example 1, washeat-treated at 1400 C. for 10 16 hours in vacuum, cooled to roomtemperature, and was tested for tensile strength at 1100" C. in vacuum.The results are given in Table III below.

EXAMPLE 9 alloys of this invention so as to make them more resistant All comprising 5% Zirconium, 15% tungsten to oxidation or the action ofcorrosive gases. ()5% boron, balance cohlmbium, was Prepared in theSince it is obvious that many changes and modifications ame manner asgiven i th previous (gxample R h can be made in the above-describeddetails without deof testing for high temperature tensile properties aregiven Parting from the nature and Spirit Of the im'tintion, it in TableIII below. is to be understood that the invention is not to be limitedTABLE III [Tensile Strength testing of Nb-Zr'IVB alloys-Heat treatment16 hrs. at1,400 C.Testcd in vacuum at 1,100 C. at a strain rate of 0.067per minute] 0.2+ Ultimate Reduction tion in Zr W C B Nb Yield Tensile inCross Gauge (p.s.i.) (p.s.i.) Sectional Length;

Area 0.125 Diem.

Alloy of Ex 5 10 0.05 13211. 40,000 52,000 20 5 15 0.05 Bal. 45,00054,800 15 0 EXAMPLES 10 TO 15, INCLUSIVE to said details except as setforth in the appended claim.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: 1. A high-strengthcolumbium-base alloy consisting Additional alloy samples were preparedin the same manner as described for the alloys of Examples 8 and 9. Inthe case of Examples 15 and 16, carbon was added in the form of a binarymaster alloy of colu-mbium containessentially of, y Weight, about 3%Zirconium, about 5 i0 ing 2% b Th specimens 30 prepared were b- 18%tungsten, and up to about 0.2% in total of the elejected tostress-rupture tests at elevated temperatures. The ments l ted from thegroup consisting of boron and results of these tests are given in TableIV below. carbon, the balance being essentially colu'mbium.

TABLE IV [Stressrupture testing of Nb-Zr-W-B-C alloysHeat treatment: 16hrs. at 1,400 C.-- Tested in vacuum at 1,100 C.]

Percent Percent Composition Elonga- Stress 'Iimc-totiou in (p.s.i.)Rupture 1"Gaugc (His) Length;

Diem.

It will be seen from the above examples that the alloys References Citedof this invention exhibit high strength at elevated tem- UNITED STATESPATENTS peratures. Moreover, the stress-rupture tests on the alloys ofthis invention, as compared with those on the Nb-Zr 2822268 2/1958 Hlx75-174 binaries, are indicative of the creep resistance of the newFOREIGN PATENTS alloys herein claimed. As a general rule, the longer the1 190 580 4/1959 France time required for a metal to rupture under agiven stress and at a given temperature, the lower the creep rate of theTHER REFERENCES metal. It will be seen from Tables 11 and IV that theMetal progress, June 9 0. article by Jahnkf, et 1 alloys of thisinvention have longer times-to-rupture Page 73 li d upon than Nb-Zrbinaries, even when far greater stresses are used, thus indicating avery siginficant improvement in CHARLES N LQVELL P i E i creepresistance.

The alloys of this invention will, of course, contain small DAVID RECKRAY WINDHAM amount of incidental impurities such as oxygen, nitrogen, 75W. B. NOLL, W. C. TOWNSEND, Assistant Examiners.

1. A HIGH-STRENGTH COLUMBIUM-BASE ALLOY CONSISTING ESSENTIALLY OF, BY WEIGHT, ABOUT 3% ZIRCONIUM, ABOUT 5 TO 18% TUNGSTEN, AND UP TO ABOUT 0.2% IN TOTAL OF THE ELEMENTS SELECTED FROM THE GROUP CONSISTING OF BORON AND CARBON, THE BALANCE BEING ESSENTIALLY COLUMBIUM. 